The present invention relates to monolithic in situ field-applied roofing surface membranes. Preferably, the surface membrane is a fabric or fiberglass imbedded low rise polyurethane adhesive covered by a waterproof and ultraviolet resistant coating, such as a silicone coating.
The present invention also relates to a new and useful method and industrial robotic device for applying coatings or other spray coated layers, in uniform thicknesses and at appropriate angles of pitch, in field applications, such as roofing applications or pavement applications.
In the roofing applications, flat roofs are often made of polyurethane foam layers, which may be covered by various coatings, such as elastomeric coatings, such as silicone. It is difficult to maintain a uniform thickness when applying a foam or elastomeric material, which by its nature rises when applied to achieve a thickness above a roof base.
Furthermore, the faster that a foam applicator passes over a surface, the less volume of foam is applied, resulting in less of a thickness of the applied foam. To achieve thicker foam layers, a spray applicator is slowed down in velocity as it passes over the roof bases, so that more foam material is discharged per square unit of space of roof base being passed over by the spray applicator.
Various attempts have been made to apply foam uniformly, such as from an applicator moving at a uniform speed along a carriage track. However, at the end of each pass of an applicator over a portion of a roof base, the discharged foam is applied twice, i.e. once at the end of the pass to the edge, and again as it starts over above the previously applied foam, until the carriage can adjust to an unsprayed area.
Field applied roofing foam surface membranes are rigid polyurethane foam surface membranes, such as manufactured by Stepan Company of Pennsylvania under the trade name STEPANFOAMS(copyright).
Stepan Company also manufactures a roofing product known as xe2x80x9clow rise polyurethane adhesivexe2x80x9d, brand name number RS 9514B, which is a concentrated polyurethane foam type adhesive often used to adhere solid rubber roof substrates to flat roof substrate structures.
However, it has not been known to imbed a low rise polyurethane adhesive with a woven polyester fabric or fiberglass layer and coat the formed substrate with silicone to create a monolithic integral roofing surface membrane for flat roofs, without the need for attaching a prefabricated roofing sheet, such as of vulcanized rubber, to the underlying roof substrate.
Furthermore, Dow Corning Corporation of Midland, Michigan manufactures silicone-based roofing coatings for weatherproofing reasons and for resisting the effects of ultraviolet light, such as the POLYCOAT(copyright) R-4000 silicone roof coating. Other prior art coatings are described in U.S. Pat. No. 3,607,972 of Kiles, et al, assigned to Dow Corning corporation, such as a room temperature vulcanizable siloxane-based block copolymer.
U.S. Pat. No. 5,253,461 of Janoski, assigned to Tremco, Inc. describes a cold-process built-up roofing system, which includes a curing adhesive with tarpaper and asphalt. The adhesive in its uncured state is substantially flowable, comprising asphalt and a compatibilizer and optionally a filler, dispersed in a curable polyisocyanate prepolymer. However, in Janoski ""461 the adhesive takes up to 10 hours to cure, unlike spontaneously cured polyurethane-based foams.
Among prior art devices for applying coatings include U.S. Pat. No. 5,381,597 of Petrove which describes a wheeled robotic device for installing shingles on roofs. While it does not concern spraying of urethane foam upon a flat roof, it does describe a movable, wheeled carriage for use upon a roof.
U.S. Pat. No. 5,620,554 of Venable, assigned to Carlisle Corporation of Syracuse, N.Y. describes an apparatus for making a composite roofing material, including a reel support for reels of prefabricated vulcanized rubber sheets, a polymeric film and fleece matting, wherein rollers advance the solid rubber sheet from its reel, which heat and stretch the rubber, binding it to the polymeric film and fleece matting.
However, in Venable ""554, there must first be a reel of a prefabricated solid rubber sheet, not an spontaneously formed monolithic roofing surface membrane.
Moreover, U.S. Pat. No. 5,872,203 of Wen describes a polyurethane adhesive for bonding polymeric roofing sheets to flat roof decks, which includes a two-component curable mixture, such as a polyurethane prepolymer and a polyol.
In addition, British patent application GB 2,055,326A of CCG Roofing Contractors, Limited describes a prefabricated polymer board that includes two layers with a fabric mesh therein. However, the fabric mesh is mechanically imbedded between the two layers during fabrication forming, and does not describe imbedding a fabric spontaneously within a polyurethane foam as the spray-applied foam rises up and through the fabric.
U.S. Pat. No. 5,248,341 of Berry concerns the use of curved walls to accommodate spray paint applicators for curved surfaces, such as aircraft.
U.S. Pat. No. 5,141,363 of Stephens describes a mobile train which rides on parallel tracks for spraying the inside of a tunnel.
U.S. Pat. No. 5,098,024 of MacIntyre discloses a spray and effector which uses pivoting members to move an armature which holds a spray apparatus.
U.S. Pat. No. 4,983,426 of Jordan discloses a method for the application of an aqueous coating upon a flat roof by applying a tiecoat to a mastic coat.
U.S. Pat. No. 4,838,492 of Berry discloses a spray gun reciprocating device, wherein parallel tracks are used wherein each track is square in cross section, but further wherein each track guides a plurality of rollers thereon.
U.S. Pat. No. 4,630,567 of Bambousek discloses a spray system for automobile bodies, including a paint booth, a paint robot apparatus movable therein, and a rail mechanism for supporting the apparatus thereat.
U.S. Pat. No. 4,567,230 of Meyer describes a chemical composition for the application of a foam upon a flat roof.
U.S. Pat. No. 4,167,151 of Muraoka discloses a spray applicator wherein a discharge nozzle is moved transversally upon a frame placed adjacent and parallel to the surface having the foam being applied thereto. However, the applicator of Muraoka ""151 does not solve the problem of excess foam being applied at the end of each transverse pass of the discharge nozzle.
U.S. Pat. No. 4,209,557 of Edwards describes a movable carriage for a nozzle applying adhesive to the back of a movably advancing sheet of carpeting. Similarly, Australian Pat. No. 294,996 of Keith describes a movable carriage for a nozzle applying a polyurethane foam coating to a movably advancing sheet.
U.S. Pat. No. 4,016,323 of Volovsek also discloses the application of foam to a flat roof.
U.S. Pat. No. 3,786,965 and Canadian Pat. No. 981,082, both of James, et al, describe a self-contained trailer for environmentally containing a dispenser for uniformly dispensing urethane foam upon a terrestrial surface, wherein the problem of xe2x80x9cskewingxe2x80x9d occurs at the completion of each pass at the boundary edges of the surface to which are urethane foam is being applied. James ""965 employs self-enclosed gantry robots to move the fluid discharge nozzle over the terrestrial surface.
U.S. Pat. No. 3,667,687 of Rivking discloses a foam applicator device.
U.S. Pat. No. 1,835,402 of Juers describes an apparatus for spraying glass from a nozzle transversely along a flat surface and U.S. Pat. No. 3,027,045 of Paasche discusses a coating machine where the nozzle moves by a pivot arm.
U.S. Pat. No. 3,096,225 of Carr discloses a hand-held spray nozzle for depositing a continuous stranded material, such as glass.
U.S. Pat. No. 2,176,891 of Crom discloses an apparatus for applying coatings over curved surfaces, such as within ditches or other curved surfaces. Moreover, U.S. Pat. No. 4,210,098 of Harrison also discloses an apparatus for spraying insulation or other coatings upon curved surfaces.
Other related art includes U.S. Pat. No. 2,770,216 of Schook for a pivotable spray nozzle, U.S. Pat. No. 3,548,453 of Garis for a transverse spray apparatus, U.S. Pat. No. 3,705,821 of Breer for a transverse spray apparatus, U.S. Pat. No. 3,867,494 of Rood, et al, also for a transverse spray apparatus, U.S. Pat. No. 3,885,066 of Schwenniger for a spray apparatus with a plurality of nozzles and U.S. pat. No. 3,923,937 of Piccoli, et al, for a centrifugally moving spray nozzle.
U.S. Pat. No. 3,954,544 of Hooker describes a method of applying a membrane covered rigid foam and a method of bonding a sheet or web, and U.S. Pat. No. 4,659,018 of Shulman discloses an orbiting nozzle apparatus.
U.S. Pat. No. 4,474,135 of Bellafiore discloses an apparatus for spraying a coating upon a spherical object supported by a post, which apparatus includes a curved track for providing orbital movement of a spray applicator about the exterior spherical surface of the sphere to be coated. While they are curved in nature, the curved tracks thereof are provided for orbital movement about the sphere, not to change the speed, tilt and direction of a linearly moving nozzle.
Another attempt to solve the problem of xe2x80x9cdouble sprayingxe2x80x9d at a pass edge has been described in U.S. Pat. No. 4,333,973 of Bellafiore, which describes a similar spray applicator, such as that of Autofoam(copyright) Company. This spray applicator includes a wheeled, self-movable vehicle having a carriage portion with a horizontal linear track thereon. The spray applicator moves from one end of the track to the other, opposite end of the track at the end of one pass, of the applicator, above a portion of a roof base, and then the applicator reverses direction upon the track.
However, to avoid the xe2x80x9cdouble sprayingxe2x80x9d problem noted above, the Autofoam(copyright) device has an on-off switch which turns the applicator off at an appropriate time at the end of a pass while the applicator is reversing direction, and re-starts the applicator a short time later when the applicator has started to move in the opposite direction.
Moreover, there are severe problems with this approach, as the constant xe2x80x9con-offxe2x80x9d starting and re-starting of the applicator causes fatigue to the metal or other material parts of the applicator, and a detrimental effect to the end product. In addition, the Bellafiore ""973 and Autofoam(copyright) devices are bulky and complicated to use.
In addition, while monolithic field applied, spontaneously sprayed polyurethane foam roofing surface membranes are convenient, they use up considerable amount of material in creating the roofing surface membrane.
Therefore, the objects of the present invention are as follows:
It is an object of the present invention to provide a monolithic, unitary integral roofing surface membrane from a combination of a low rise polyurethane adhesive, a reinforcing mesh and a weather proofing and ultraviolet resistant coating.
It is also an object of the present invention to provide a thin monolithic reinforced roofing surface membrane which cures spontaneously.
It is also an object of the present invention to provide a thin but durable reinforced roofing surface membrane for roofs.
It is yet another object of the present invention to provide a method of applying a fabric or fiberglass mesh within a spontaneously curable polymer roofing surface membrane while the polymer is being spontaneously cured at a roofing field application.
It is further an object of the present invention to provide a method and apparatus for providing monolithic fabric and/or fiberglass reinforced roofing surface. membranes.
It is another object of the present invention to provide a spray applicator for foam roofing which applies a coating of elastomeric foam of uniform thickness.
It is also an object of the present invention to provide a single yet efficient spray applicator for foam roofing.
It is also an object of the present invention to provide a spray applicator that can be disassembled into a few major parts for easy transport and reassembly on a roof without resorting to the use of a crane.
It is yet another object of this invention to provide a method for covering a large area of a roof with foam roofing using a continuous spray.
It is also an object of the present invention to provide a spray applicator with a nutating nozzle mount to minimize variations in coating thickness.
It is a further object of the present invention to provide a hand-held remote control to enable the spray applicator vehicle to operate without an on-board operator.
It is an object of the present invention to provide a method for continuous adhesive spraying and application of elastomeric sheet roofing material of large strip areas of a roof.
It is a further object of the present invention to provide accessories for the spray applicator vehicle to permit its use for applying elastomeric sheet roofing material from a roll.
It is also an object of the present invention to improve over the disadvantages of the prior art.
In keeping with these objects and others which may become apparent, and to solve the problems inherent in the Bellafiore ""973 and Autofoam(copyright) spraying devices, the present invention uses one or more track rails, such as a double linear track of round cross section, as shown in the drawings herein, to continuously apply monolithic polyurethane roofing surface membranes.
In one embodiment, there is an arcuate uphill end portion of the track at each side, so that the spray applicator, which moves along the one or more linear tracks, will accelerate in speed and tilt the discharge nozzle outward as it rolls up the curved uphill portion, thereby reducing the amount of foam applied to the edge portion of the roof at the end of a pass of the applicator.
To obviate the complicated mechanisms of the Autofoam(copyright) device, the present invention uses simple mechanics to move the spray applicator. For example, a transverse linear movement means, such as, a radially extending swinging arm, is provided for the sideways movement of the applicator along the track. To eliminate arcuate movement of the pivoting arm, the transverse linear movement means may have a telescoping mechanism or other gear assembly, so that the spray applicator moves linearly, instead of arcuately. For example, the swinging arm moves about a pivot fulcrum point.
Other transverse movement mechanisms may be used, such as rack and pinion devices.
To further insure uniform thickness, the present invention further comprises various speed controls, so that an appropriate thickness can be applied for each pass.
For example, a rheostat controls the speed of the movement of the spray applicator, and an LED readout tachometer has a display dial with appropriate readings for appropriate speeds for corresponding desired thicknesses. Since the rate of flow of foam-producing material emanating from the nozzle is fixed, the ground movement speed of the applicator determines the weight of the coating per unit area applied. This, in turn, determines the thickness.
When a slope is desired on a flat roof, such as toward a drainage line, the ground speed of the foam applicator can be reduced on each successive pass away and parallel to the drainage line. This will result in a stepwise slope approximating the desired contour.
It has been found that a nutating nozzle holder, which tilts the nozzle a small amount cyclically as it traverses the track, can be used to minimize the variations in foam thickness (in the form of rounded ridges) due to the hollow-cone pattern of the nozzle.
Accessories can be added to the spray applicator so that it can be adapted for spraying adhesive on a roof or for automatically laying an elastomeric sheet covering such as Sure-SealTm(trademark) Fleece Back 100 EPDM made by Carlisle SynTec Incorporated of Carlisle, Pa. over a polyurethane foam substrate. Accessories can also be added for imbedding reinforced fabric within the polyurethane foam substrate.
In one embodiment, the primary roofing surface membrane is a polyurethane foam, such as STEPANFOAMO(copyright) of Stepan Corporation. In this embodiment, the average thickness of the deposited foam is about two inches in thickness.
However, in the preferred embodiment, instead of a standard polyurethane foam roof surface membrane of about 2 inches in thickness, the preferred monolithic roof surface membrane is much thinner, rising to a thickness of about one quarter (xc2xc) inch in thickness.
This is because, instead of using standard polyurethane foam such as STEPANFOAMS(copyright), what is used is what is known in the trade industry as a xe2x80x9clow rise polyurethane adhesivexe2x80x9d, such as brand name number RS9514B, also manufactured by Stepan Corporation.
Previously, low rise polyurethane adhesives have only been used to act as an adhesive to adhere prefabricated roofing, such as vulcanized rubber sheets, to roof deck surfaces.
These low rise polyurethane adhesives have not previously been used as a component of a monolithic roofing surface membrane itself.
The combination of low rise polyurethane adhesive with a reinforcing mesh and a silicone-based coating obviates the need for a thick polyurethane foam base of about two inches.
Therefore, the present invention includes a field applied, monolithic roofing surface membrane, which includes a combination of a low rise polyurethane adhesive with a fabric or fiberglass mesh adding reinforcement thereto, such as a woven polyester, i.e., what is known as a 6 or 10 ounce fabric mesh.
The mesh is applied to the low rise polyurethane adhesive from a rolling reel and is embedded within the polyurethane adhesive by virtue of the rising, spontaneously cured polyurethane adhesive contacting and rising through the recess spaces between the fabric or mesh structural fibers, thus encasing the mesh within the polyurethane adhesive during the curing of the polyurethane adhesive.
In the preferred embodiment of the present invention, a subsequent application of a silicone-based coating is applied also by spray nozzle over the already-deposited and mesh reinforced low rise polyurethane adhesive surface membrane.
This silicone coating adds a seal for weather proofing the underlying mesh reinforced polyurethane adhesive layer and for resisting damage from ultraviolet light. A typical silicone coating is POLYCOAT 4000 of Dow Corning Corporation, or as described in U.S. Pat. No. 3,607,972 of Kiles, et al, assigned to Dow Corning Corporation.
When the silicone coating is applied, it has a thickness of about 20 mils. The thickness of the reinforcing mesh layer and the silicone coating together is about 30-100 mils. The total thickness of the preferred monolithic roofing surface membrane, including the silicone coating and the mesh-reinforced polyurethane adhesive, is about one quarter (xc2xc) inch in thickness, which is significantly thinner than the two (2) inch thickness of a spray applied foam roofing substrate.
While the invention has been described for use in applying roofing materials on roofs, it is also usable for spray applications at ground level such as for pavement painting or sealing applications.